1. Field of the Invention
The present invention relates to a device for longitudinal adjustment of a spreader relative to the yoke beam with a sled for lateral adjustment of the spreader between the supports of a straddle carrier for picking up and transporting containers. The device is made up of a base frame and mountings for support bolts firmly connected with it, a traverse with openings for support bolts and an attachment for a displacement cylinder, support bolts between the mountings and the traverse, and displacement cylinders between the base frame and the traverse.
The invention can be used anywhere where spreaders are disposed between the supports of a portal lift truck via yoke beams and their sleds for lateral adjustment of the spreader, and where longitudinal positioning of the spreader must take place without the lift truck moving in the longitudinal direction relative to the container.
2. The Prior Art
Spreaders for grasping and transporting containers are known both on portal cranes and on portal lift trucks. The portal lift trucks, so-called straddle carriers, serve to pick up containers on land, transport them, and set them down again at a specific point. Spreaders are provided as the load accommodation means for holding and transporting the container. They can be adjusted to various container sizes and have four twist lock accommodations. These twist lock accommodations engage into the corners of the container, are rotated, and thereby produce a releasable connection between the spreader and the container.
A spreader for picking up and transporting containers on a straddle carrier is known from DE 103 55 946 A1. In this spreader, a direct suspension between each yoke beam and the spreader is present. The coupling points are directly set by an adjustment device and adjusted in the longitudinal direction relative to the spreader, and a connection construction is disposed between each yoke beam and each suspension point. The adjustment devices disposed laterally, which represent cylinders, however, also serve for suspension of the spreader, in part, thereby causing great bending forces to act on the cylinders and to lead to their premature wear.
A spreader for transporting containers is known from U.S. Pat. No. 4,093,090, which consists of two frames that are displaceable, relative to one another, in the longitudinal direction, whereby this spreader is not suitable for attachment to a sled that is disposed within a yoke beam, which is situated on the supports of a straddle carrier.
A spreader with flat guidance for picking up and transporting containers on a straddle carrier is described in DE 20 2006 017 624 1, which spreader is disposed on two yoke beams with laterally adjustable sleds, whereby yoke beams are guided between the supports of a straddle carrier. Two containers at the same time, in each instance, can be picked up with the spreader. A connection crosspiece relieves stress on the adjustment devices, and hydraulic cylinders are disposed parallel to the connection crosspieces as adjustment devices. These spreaders, too, demonstrate great wear, because the connection crosspieces are exposed to very great stresses even if the device is designed for only one container. Furthermore, this device also results in a disadvantageous height for the vehicle.